(1) Field of the Invention
The present invention relates to an electric junction box to be mounted on a motor vehicle and so on as a mobile unit.
(2) Description of the Related Art
Generally, a motor vehicle as a mobile unit mounts various electronic instruments such as lamps, for example, a head lamp and tail lamp and motors, for example, a starter motor and motor for an air conditioner.
In order to supply electric power to the various electronic instruments, the motor vehicle arranges junction blocks at appropriate positions. The junction block is composed by integrating various many electric circuit units such as fuses and relays.
The junction block may be called a fuse block, relay box or electric junction box (for example, see Japanese Patent Application Laid-Open No. 2005-119331) as a generic term since the junction block may include fuses, relays and/or busbars. In this specification, such a fuse block, relay box or junction block is called an electric junction box as a generic term.
The electric junction box disclosed in Japanese Patent Application Laid-Open No. 2005-119331 includes: a box body forming an outer shape of the electric junction box; and a wiring block. The box body is made of electrically insulating synthetic resin and formed in a box-shape. The box body includes: a mounting part on which electric components such as relays and fuses are mounted; and a connector fitting part to which connectors of a wiring harness are fit.
The wiring block is received in the box body. The wiring block includes busbars through which electric power is supplied from a battery or electric generator as a power supply and which branches off electric wires to the mounting parts on which the electric components are mounted.
The busbar is made of electrically conductive sheet metal. The busbar includes: a power supply connecting part connected to the battery or electric generator; and a terminal part which is positioned in the mounting part so as to be connected to the electric component such as a relay or fuse when the wiring block is received in the box body.
The wiring block electrically connects the power supply, electric components and electric wires of a wiring harness to each other according to a predetermined pattern, so that the electric junction box electrically connects the power supply, electric components and electronic instruments connected to the respective electric wires of the wiring harness to each other according to a predetermined pattern. Then, the electric junction box supplies electric power supplied from the power supply to the electric components through the wiring harness.
As for the electric junction box disclosed in Japanese Patent Application Laid-Open No. 2005-119331, when the motor vehicle is subjected to a collision at the front face by another motor vehicle on a condition that the electric junction box is arranged at the front in an engine room of a motor vehicle, off course, the motor vehicle is damaged, for example, the box body is crushed, causing that the wiring block is unable to branch off the electric power, that is, the electric power is hardly supplied to the electronic instruments.